The present invention relates generally to the generation of video graphic images, and more specifically to the generation of three-dimensional stereoscopic images on video displays.
Various methods exist for generating 3-D images on computer monitors. One type of three-dimensional (3D) image provides a planer three-dimensional image using shading, sizing, and texturizing techniques. Stereoscopic images have been used in order to provide 3-D images that appear to stand out from the plane in which they lie by providing different views to the right eye and the left eye. Alteration of the views creates an illusion that the image is in three-dimensional space as opposed to on the plane of the monitor.
One method of producing 3-D stereoscopic images is to project images onto a screen using different polarized light sources. By projecting a right eye image using a polarized lens having a first orientation, and projecting a left eye image using a different polarized lens having a second orientation orthogonal to the first orientation it is possible for a viewer to observe 3-D images by wearing special glasses. Specifically, each lens of the glasses is polarized and oriented such that the angle of polarization of the lenses is orthogonal to one another to match the polarization of the projected picture. As a result, each eye receives a different image resulting in 3-D images being observed.
By aligning the right lens of the glasses in the same polarization plane as the right lens of the projector, the right eye will see those images projected specifically for the right eye. Likewise, the left lens of the glasses are aligned in the same polarization plane as the left lens of the projector, as a result, the left eye will see those images projected from the left eye projector lens. By aligning the left and right eye lenses orthogonally, it is possible prevent images generated for the opposite eye from being viewed.
The use of polarization techniques is feasible where projection methods are used. However, where projection methods are not used, such as with a monitor used with a personal computer, the ability to individually polarize left and right eye images becomes cost prohibitive.
One method of overcoming the need for polarization of images is to sequentially provide separate left and right eye images in synchronization with special eyeglasses capable of sequentially blocking or transmitting light. This is generally accomplished by controlling each of the right and left lenses of the glasses to be opaque or transparent as needed. In other words, a frame containing left eye data would be synchronized with a pair of viewing glasses such that the left lens of the glasses would be transparent during the left eye frame. During a subsequent right eye frame, the left eye lens would be opaque, while the right eye lens would be transparent. This would allow the image to be seen by only the right eye. By using such an alternating technique at appropriate refresh rates, it is possible to produce the illusion of a 3-D graphics being viewed on a monitor.
One drawback of generating three-dimensional graphics in memory is that in order for each eye to interpret its image as a continuous picture, it must receive the images at a frame rate of approximately 60 hertz. This requires a total frame rate of 120 hertz or better (60 Hz for each eye). This refresh rate is not currently achievable by LCD panels that are beginning to replace traditional monitors. Monitors that can achieve this high frame tend to be cost prohibitive. In addition to monitor limitations, the hardware associated with providing the increased frame rate and the actual viewing glasses or lenses can also be costly.
Therefore, a method and apparatus that would overcome problems associated with the prior art viewing of 3-D images would be desirable.